Method and means for the production of foil material



Oct. 21, 1947. c. s. MUNTERS METHOD AND MEANS FOR THE PRODUCTION OF FOILMATERIAL Filed Jan. 5, 1943 2 Sheets-Sheet 1 Fig.1

HYYENTV'R A W Wv METHOD AND MEANS FOR THE PRODUCTION OF FOIL MATERIAL QM *w Patented Oct. 21, 1947 METHOD AND MEANS FOR THE PRODUC- TION OFFOIL MATERIAL Carl Georg Munters, Stocksund, Sweden Application January5, 1943, Serial No. 471,345

In Sweden April 6, 1939 6 Claims. 1

My invention relates to sheet material for instance such as is used forpackages. Furthermore, the invention relates to sheets which consist ofan artificial mass which softens when heated and which preferably istransparent. The sheets are provided with corrugations, bulges or thelike, and two or more sheets may be united with each other at the topsof these corrugations or bulges in a manner such that a composite boardor wall is obtained which is comparatively 2 I of steam which isconducted in a known manner through the interior of the rollers. It ispreferable to preheat the film 28, prior to its entrance between therollers 28, 29, to a temperature corresponding, approximately at least,to the temperature of these rollers. Such preheating may rigid orresistive against bending in one direction at least.

To provide such corrugations, the sheets may be folded in the cold statein a suitable machine so as to produce more or less sharp edges.However, this method is not suitable, particularly for packages composedof transparent sheets, for the reason that the sheets are apt to breakon account oftheir relative brittleness, which impairs their strengthand appearance in the finished packaging material. Moreover, thecorrugations are not of uniform shape when made in this way which, interalia, also impair the strength of the package. In addition, this methodis limited to constructions with sharp rectilinear pleats over thesurface of the sheet, and consequently, for instance, it is not possibleto impart a softly rounded shape to the pleats.

It is the object of the invention to overcome these difficulties and toattain a continuous and economic production of the sheet material.

Further objects and advantages of the invention will be apparent fromthe following description considered in connection with the accompanyingdrawings which form a part of this specification, and of which:

Fig. 1 shows a machine more or less diagrammatically and partly insection, for the production of sheets according to the invention.

Fig. 2 shows a modified machine partly in section in accordance with theinvention.

Fig. 3 is a sectional view on the line IH-III of Fig. 2.

In Fig. l, 25 denotes a rotatably mounted roller having a roll oftransparent material, such as acetyl cellulose, wound thereon. From thisroll, the film 26 is conveyed, if desired over a guide roller 21, inbetween two rollers 28, 29, the ex-- ternal surfaces of which are formedwith a profile corresponding to the desired shape of the films. In thepresent case, the rollers are provided with axially extending tooth-likeprojections engaging one another, as will be seen from the figure. Therollers 28, 29 are heated to a suitable temperature, for instance withthe aidbe effected with the aid of one or more preheating rollers, or bymeans of hot air, and the web may be heat-insulated, as at 50. The film28 is corrugated during its passage through the teeth meshing with eachother. By reason of the heatingprocedure the film has become soft andplastic. The film remains in the teeth of the roller 29 during itscontinued rotation and passes between this roller and another roller 30,provided with teeth in mesh with the teeth of the roller 29. Devicesknown per se are preferably made use of to loosen the film from theroller-28 and to keep the same in the teeth of the roller 28. The roller30 need not press against the roller 29, a certain play being preferablyprovided between the teeth thereof. Preferably, the roller 30 is drivenby means of a synchronizing gear, so that contact between the rollerteeth and iamming of the film will not occur. The film can thusconveniently move laterally under the change in temperature occurring bythe fact that the roller 30 is comparatively cold or cooled and of sucha temperature that the film becomes set and rigid so as to retain thecorrugated shape thereof.

Arranged beside the roller 30 is a device for applying adhesive orsolvent, such as acetone, on the ridges of the corrugated film. In Fig.1, this device is representated diagrammatically bya receptacle 3|,containing the adhesive or solvent, and a rotatable roller or the like32, which dips down into the receptacle H with the lower portion thereofand makes contact with the film car ried by the roller 30. If desired,the roller 32 may be adapted to be thrown out of engagementautomatically, when the machine is stopped, to prevent the film frombeing dissolved by the acetone and from sticking to the roller 30.

. A rotatably mounted roller 33 carries another roll of film, preferablyof the same transparent material as the film 26. From this roll, a web34 is conveyed over a roller 35 having a cylindrical external surface,said latter roller being pressed against the roller 30 for instance bymeans of springs or the like. The corrugated film 26 and the plane film34 are secured to each other during their passage between the rollers 30and 85.

The two united films may now be removed transparent material as that ofthe films 26,-

from which a web 40 is conveyed over the roller 38. By means of a device3|, 32 of the type above described, the free ridges of the corrugatedfilm 36 are moistened with solvent or adhesive substance such asacetone, the web 40 being secured to these ridges between the rollers31, 38. An enless belt 42 may be provided between the roller 31 and aroller 4|. In the same manner, a belt 43 extends between the roller 38and a roller 44. The portions of the belts 42, 43 facing one another maybe adapted to cooperate with supporting rollers 45 to keep the beltsproperly spaced from one another so as to cause the belts to press onthe sheet. During the passage of the sheet between the belts 42, 43 theattaching of the films to each other is ensured. The sheet is driedbetween the belts, if desired with the aid of a fan producing an aircurrent between the films. For the same purpose, the sheet may be heatedduring its passage between the belts 42, 43, for instance by means ofhot air.

Those portions of the webs where the solvent is applied, may besurrounded by casings 5i and 46, respectively, to prevent said substancefrom escaping freely into the surrounding atmosphere. A suction pump 41may communicate with the casing 46 through a conduit 48. The pump 41sucks out the air containing the solvent, to a receptacle 49 containinga suitable absorbing agent, such as silica gel.

The preheating of the film 26 prior to its entering between the rollers28, 29 is of importance to bring about a uniform and smooth surface, itbeing found that the material according to the invention most frequentlyhas, as compared with paper, for example, a very great coefficient ofheat expansion, which results in creasing or buckling of the films ifthey are warmed while being jammed between the rollers when beingcorrugated. During th heating proper, the film thus is permitted toexpand freely. In order also to avoid tensions in the films, during theinterconnection of the same, by reason of the high coefficient ofexpansion of the material, it is of great importance that the two films26, 34 have substantially the same temperature. On the other hand,should'the films have different temperatures, the cooling of the warmfilm will cause a contraction of the same, which results in creasing orbuckling of the cold film. Many advantages are gained by the fact thatthe rollers 30 and 35, respectively, and the films are relatively cold.Thus solvents, such as acetone, having a boiling point lower than thetemperature required for the deformation of the films, may be used toadvantage, without the substance in consideration boiling off. By reasonof the fact that the rollers 30, 35 and the films bearing thereon arecold or at room temperature, it will be possible even to unite films ofmaterials of different coefllcients of expansion Without disadvantage.If the solvent causes a temporary expansion of the one film, thetemperature of the other may be chosen higher in a manner such that,after the solvent has evaporated and both films are cooled down to roomtemperature tensions in the films, that may cause creases and the like,are eliminated. A further important property according to the inventionis, as will appear from the above, that the temperature be selected sothat the occurrence of unfavorable tensions in the finished product isavoided as far as possible.

With respect to the appearance of the films, it is of importance thatthe acetone or the solvent or adhesive substance be applied to th topsof th corrugations.

In the apparatus above described, the attaching of the transparent filmsto each other takes place continuously. After the sheet composed ofthree films has passed between the belts 42 and 43, it may be cut, forinstance, into suitable lengths. The invention also includes aconstruction, wherein the finished sheet only consists of one plane andone corrugated film, as indicated at 36. A sheet composed in this mannermay be wound onto rollers without difiiculty.

Furthermore, it is obviously conceivable to secure more than three filmsto each other, for instance in such a manner that alternate films areplane and intermediate ones are corrugated. As a material for the films,so-called secondary acetyl cellulose will be found particularlysuitable, permitting of being shaped at 90-130 degrees Centigrade. Inplace of acetone or methyl ketone, which boils at 56 to 58 degreescentigrade, methyl-ethylen ketone may be employed. As a further examplof solvents may be mentioned methyl glycol acetate with a boiling pointof 138-152 degrees centigrade, which is particularly serviceable whenpasting is effected in a warm state. So-called primary acetyl cellulosemay also be used in certain cases. Examples of such acetyl cellulose areviscos and Cellophane.

In certain cases, it may be suitable, for instance in order to permit alateral expansion of the film, to arrange the rollers 28 and 29relatively to each othe in a manner similar. to the arrangement of therollers 29, 30, as described hereinbefore.

In Figs. 2 and 3, H0 is the frame of the machine, which carries a rollerIII provided with an outer profile II2 corresponding to the desiredshape of the foils. In the present case, the roller III is formed withaxially extending teeth. The roller III is rotatably mounted in bearingsIII rigidly connected with the frame llll. Fitted into an internal borein the roller with a small clearance therein is a stationary shaft II4which is rigidly connected to the frame. The cylindrical externalsurface of the stationary shaft H4 is cutaway over a portion of theperiphery of the surface to form a recess I I5 having an axial lengthcorresponding to the length of the teeth I I2. The recess II5communicates through a passage II. and a pipe I II with a vacuum pump(not shown). A recess H8 is arranged adjacent to said recess H5 whilebeing separated therefrom, and may either communicate with theatmosphere or be supplied with air under pressure from a source ofpressure through an axial channel 9 in the shaft H4 and a conduit I20.Furthermore, the shaft I I4 has an inner recessi 2 I, which is adaptedto be traversedby a heating medium, such as steam, oil or the like,which is introduced through a passage I22 and a pipe I23 extending overthe major portion of the length of the recess Hi. The steam escapesthrough a channel I24, which is located in the same end of the shaft asthe passage I22. The roller I I I is provided with radial passages I25extending therethrough, said passages opening at the bottom of the teethII2. As

will appear from the figures, these passages may be arranged instaggered relation to each other.

and in which is provided a stationary shaft I2i with a small clearance.The shaft I21" is provided with an internal recess I28, to which issupplied a heating medium through a pipe I29 similar to the pipe I23.Furthermore, the shaft I21 is preferably formed with an outer recess I30which may communicate with the atmosphere, or which may have air underpressure supplied thereto. The outer peripheral portion ofthe roller I26carries teeth adapted to engage the teeth H2 of the roller III. Radialpassages I25 extend from the inside of the roller to the bottom of theteeth thereof.

A third roller I3I is formed with teeth engaging the teeth of the rollerIII. The roller I3I is provided with an inner bore having a stationaryshaft I32 fitted into the same. The shaft I32 is provided with a recessI33 extending from the surface thereof, sald recess communicating with avacuum source through a passage I3I. Furthermore, the roller I3I isprovided with an inner recess I35 traversed by a cooling agent, such aswater, which may be introduced through a pipe conduit I36 of the sameshape as that of the conduit I23.. Immediately adjacent to' the recessI83 but separated therefrom, there is provided a groove or channel I 37in the surface of the shaft I32, said. groove or channel communicatingwith the atmosphere or with a source of compressed air. The roller I3Iis provided, similar to the other rollers, with radially extendingpassages I25.

Bearing on the roller I3I is a roller I38 having a smooth cylindricalouter surface. If desired, special means may be provided to bring aboutor to control a suitable pressure between the rollers WI and I38. InFig. 2, I39 designates a receptacle for a solvent such as acetone.Dipping into this solvent is a roller Iifl or the like, while anotherroller III bears on said roller as well as on the ridges of the foil webengaging the roller I3I. The rollers Md and IIII are rotatable, so thatsolvent will be conveyed by means of the same to the ridges orundulation crests of the foils. If

desired, the rollers Hit and MI may be enclosed -within a casing I52.

The recess H5 in the shaft II extends in a peripheral direction betweenor substantially between the points of engagement of the roller III withthe rollers I23 and I3I. The partition separating the recesses II5 andH8 is located right opposite the point of tooth engagement between therollers II I and ISI or somewhat in advance of said point. The recessI33 inthc shaft I32 extends between the points of engagement or contactbetween the roller I3I and the rollers I I I and I33.

A web N3 of acetyl cellulose, for example, is conveyed from a rollthrough a space bounded by walls I48 adapted to supply heat to the webso as to preheat the same. The web may slide on the one wall of thespace so as to increase the heat transmission. The web then passesbetween two rollers Ills provided with heating devices, the latterrollers also ensuring that the web is maintained altogether uniform andsmooth. After that the web is led in between the teeth of the rollersIII and I26 so as to be corrugated thereby. The webis then maintained inthe teeth of the roller III, which is ensured according to the inventionby the fact that the surface of the web facing the roller is held bysuction to these teeth by means oi the partial vacuum existing withinrecess H5 and communicated through the passages I25 to the web. Tofacilitate the removal of the web from the engagement with the teeth ofthe roller I28. air under pressure may be-introduced through the recessI30, said air causing a pressure on the web through the passages I25 ina direction from the roller I28. When the web reaches the point ofengagement between the rollers III and I 3|, the communication isinterrupted between the corresponding passages I25 and the recess -I I5.At the same time, the pressure below atmospheric retaining the web tothe roller II I ceases. The web is instead subjected to a sucking effectfrom the passages I25 in the roller I3I communicating with the recessI33 of the shaft I32, which results in release of the web from itsengagement with the teeth of the roller III, and is transferred onto theteeth of the roller I3I. In the embodiment according to Figs. 2 and 3,the compressed air escaping through the passages I25 located oppositethe recess IIB facilitates the release of the'web from the teeth of theroller III,

and at the same time presses it against the teeth of the roller I3I. Toincrease this pressing effect, a plate I 45 may be provided, if desired,between and over the sides of the rollers III and I3I, so that thecompressed air escaping from the recess H8 is urged against the weblyingon the roller I3I. If desired, the plate I45 may be provided with one ormore apertures connected to a source of compressed air.

The web is cooled down by the roller -I3l and will maintain its form.The rollers I40, III moisten the .undulation crests with" solvent.Therefore, when a second web I46 is introduced between the smooth rollerI38 and the roller I3I, the two webs will be pasted together so that acomposite sheet is obtained, as indicated at 61 in Fig. 2.

While several embodiments of the invention have been shown, it is to beunderstood that these are for purpose of illustration only, and that theinvention is not to be limited thereby, but its scope is to bedetermined by the appended claims.

What I claim is:

l. The method of continuously forming a foil of thermoplasticmaterialhaving a multiplicity of projections and depressions which includesfeeding a sheet of such foil through a heating zone to soften it whilepermitting thermal expansion of the heated material, forming the desiredprojections and depressions in the softened foil by applying pressure tothe opposite sides of the foil, carrying the formed foil in its softenedstate from the forming station on a heated supporting surface to preventdeformation of the foil, stripping the foil from said heated surface andtransferring it to a chilling surface providing support for andpermitting relatively free contraction of the formed foil, and carryingthe foil on said chilling surface to cool and set the foil in its formedstate.

2. The method of continuously forming thermoplastic material comprisinga foil having a multiplicity of projections and depressions and having abacking sheet which includes feeding a sheet of such foil through a.heating zone to soften it while permitting thermal expansion of theheated material, forming the desired projections and depressions in thesoftened foil by applying pressureto the opposite sides of the foil,

carrying the formed foil in its softened state from the forming stationon a heated supporting surface '0 prevent deformation of the foil,stripping t e foil from said heated surface and transferring it to achilling surface providing support for and permitting relatively freecontraction of the formed foil, carrying the foil on said chillingsurface to cool and set the foil in its formed state, and attachingto:the crests of the projections n the formed foil a backing sheet ofthermoplastic material at approximately the same temperature as that ofthe formed foil.

3. The method of continuously forming thermoplastic material having amultiplicity of projections and depressions and a backing sheet whichincludes feeding a sheet of such foil through a heating zone to softenit while permitting thermal expansion of the heated material, formingthe desired projections and depressions in the softened foil by applyingpressure to the opposite sides of the foil, carrying the formed foil inits softened state from the forming station on a heated supportingsurface to prevent deformation of the foil, stripping the foil from saidheated surface and transferring it to a chilling surface providingsupport for and permitting relatively free contraction of the formedfoil, carrying the foil on said chilling surface to cool and set thefoil in its formed state, applying a solvent to the crests of theprojections of the foil and pressing a backing sheet of thermoplasticmaterial at approximately the same temperature as that of the foil tothe solvent treated crests.

4. The method of continuously forming a foil of thermoplastic materialhaving a multiplicity of projections and depressions which includesfeeding a sheet of such foil through a heating zone to soften it whilepermitting thermal expansion of the heated material, maintaining thefilm hot up to the time it comes in contact with the first formingroller, forming the desired projections and depressions in the softenedfoil by applying pressure to the opposite sides of the foil, carryingthe formed foil in its softened state from the forming station on aheated supporting surface to prevent deformation of the foil, strippingthe foil from said heated surface and transferring it to a chillingsurface providing support for and permitting relatively free contractionof the formed foil, and carrying the foil on said chilling surface tocool and set the foil in its formed state. 7

5. In apparatus of the character described, a heating de'ice forsoftening a moving foil of thermoplastic material while providing forthermal expansion of the foil, a first and a second forming rollerprovided with intermeshing projections and depressions, means forheating said rollers, means for passing the softened foil between saidrollers to form it, means for maintaining the film hot between saidheating means and where it passes between said heated rollers, means forstripping the formed foil from the first roller and carrying it in itssoftened state on the surface of said second roller away from theforming station, a chilling roller having projections and depressionsmeshing with said second roller and engaging said foil at a place spacedfrom said forming station to effect a preliminary setting of thesoftened foil while it is supported by said second roller and means forstripping the foil from said second roller and carrying it in its formedstate on the surface of said chilling roller to further cool and set thefoil.

6. In apparatus of the character described a heating device forsoftening a moving foil of thermoplastic material while providing forthermal expansion of the foil, first and second forming rollers providedwith intermeshing projections and depressions, passageways between saiddepressions and the interior of said rolls, means for introducing airunder pressure into the passageways in said first roll to strip theformed foil therefrom, means to introduce a vacuum in the passageways ofsaid second roll over a portion of the circumference thereof to hold thefoil on said second roll, means associated with said second roll tointroduce air under pressure into said passageways to strip the foiltherefrom at a predetermined position in the rotation thereof, achilling roller having projections and depressions meshing with saidsecond roller and engaging said foil to effect a preliminary setting ofthe softened foil while it is supported by said second roller,passageways formed in said second roller between said depressions andthe interior thereof, means for introducing a vacuum into saidpassageway in said chilling roll to retain the foil thereon during aportion of one rotation thereof and means for introducing air underpressure into said passageways at a predetermined rate in the rotationof said chilling roller to strip the foil therefrom.

CARL GEORG MUNTERS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,981,338 Swift, J1 NOV. 20, 1934657,100 Ferres Sept. 4, 1900 1,146,771 Raflel July 13, 1915 1,473,096H111 et al. NOV. 6, 1923 1,264,506 Hahn Apr. 30, 1918 2,018,240 Swift,Jr. Oct. 22, 1935 1,595,346 Long et al A118. 10, 1926

